// StreamUtils.cs
//
// Copyright 2005 John Reilly
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library.  Thus, the terms and
// conditions of the GNU General Public License cover the whole
// combination.
// 
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent
// modules, and to copy and distribute the resulting executable under
// terms of your choice, provided that you also meet, for each linked
// independent module, the terms and conditions of the license of that
// module.  An independent module is a module which is not derived from
// or based on this library.  If you modify this library, you may extend
// this exception to your version of the library, but you are not
// obligated to do so.  If you do not wish to do so, delete this
// exception statement from your version.

using System;
using System.IO;

namespace ICSharpCode.SharpZipLib.Core
{
    /// <summary>
    /// Provides simple <see cref="Stream"/>" utilities.
    /// </summary>
    public sealed class StreamUtils
    {
        /// <summary>
        /// Read from a <see cref="Stream"/> ensuring all the required data is read.
        /// </summary>
        /// <param name="stream">The stream to read.</param>
        /// <param name="buffer">The buffer to fill.</param>
        /// <seealso cref="ReadFully(Stream,byte[],int,int)"/>
        public static void ReadFully(Stream stream, byte[] buffer)
        {
            ReadFully(stream, buffer, 0, buffer.Length);
        }

        /// <summary>
        /// Read from a <see cref="Stream"/>" ensuring all the required data is read.
        /// </summary>
        /// <param name="stream">The stream to read data from.</param>
        /// <param name="buffer">The buffer to store data in.</param>
        /// <param name="offset">The offset at which to begin storing data.</param>
        /// <param name="count">The number of bytes of data to store.</param>
        /// <exception cref="ArgumentNullException">Required parameter is null</exception>
        /// <exception cref="ArgumentOutOfRangeException"><paramref name="offset"/> and or <paramref name="count"/> are invalid.</exception>
        /// <exception cref="EndOfStreamException">End of stream is encountered before all the data has been read.</exception>
        public static void ReadFully(Stream stream, byte[] buffer, int offset, int count)
        {
            if ( stream is null ) {
                throw new ArgumentNullException(nameof(stream));
            }

            if ( buffer is null ) {
                throw new ArgumentNullException(nameof(buffer));
            }

            // Offset can equal length when buffer and count are 0.
            if ( (offset < 0) || (offset > buffer.Length) ) {
                throw new ArgumentOutOfRangeException(nameof(offset));
            }

            if ( (count < 0) || (offset + count > buffer.Length) ) {
                throw new ArgumentOutOfRangeException(nameof(count));
            }

            while ( count > 0 ) {
                int readCount = stream.Read(buffer, offset, count);
                if ( readCount <= 0 ) {
                    throw new EndOfStreamException();
                }
                offset += readCount;
                count -= readCount;
            }
        }

        /// <summary>
        /// Copy the contents of one <see cref="Stream"/> to another.
        /// </summary>
        /// <param name="source">The stream to source data from.</param>
        /// <param name="destination">The stream to write data to.</param>
        /// <param name="buffer">The buffer to use during copying.</param>
        public static void Copy(Stream source, Stream destination, byte[] buffer)
        {
            if (source is null) {
                throw new ArgumentNullException(nameof(source));
            }

            if (destination is null) {
                throw new ArgumentNullException(nameof(destination));
            }

            if (buffer is null) {
                throw new ArgumentNullException(nameof(buffer));
            }

            // Ensure a reasonable size of buffer is used without being prohibitive.
            if (buffer.Length < 128) {
                throw new ArgumentException("Buffer is too small", nameof(buffer));
            }

            bool copying = true;

            while (copying) {
                int bytesRead = source.Read(buffer, 0, buffer.Length);
                if (bytesRead > 0) {
                    destination.Write(buffer, 0, bytesRead);
                }
                else {
                    destination.Flush();
                    copying = false;
                }
            }
        }

        /// <summary>
        /// Copy the contents of one <see cref="Stream"/> to another.
        /// </summary>
        /// <param name="source">The stream to source data from.</param>
        /// <param name="destination">The stream to write data to.</param>
        /// <param name="buffer">The buffer to use during copying.</param>
        /// <param name="progressHandler">The <see cref="ProgressHandler">progress handler delegate</see> to use.</param>
        /// <param name="updateInterval">The minimum <see cref="TimeSpan"/> between progress updates.</param>
        /// <param name="sender">The source for this event.</param>
        /// <param name="name">The name to use with the event.</param>
        /// <remarks>This form is specialised for use within #Zip to support events during archive operations.</remarks>
        public static void Copy(Stream source, Stream destination,
            byte[] buffer, ProgressHandler progressHandler, TimeSpan updateInterval, object sender, string name)
        {
            Copy(source, destination, buffer, progressHandler, updateInterval, sender, name, -1);
        }

        /// <summary>
        /// Copy the contents of one <see cref="Stream"/> to another.
        /// </summary>
        /// <param name="source">The stream to source data from.</param>
        /// <param name="destination">The stream to write data to.</param>
        /// <param name="buffer">The buffer to use during copying.</param>
        /// <param name="progressHandler">The <see cref="ProgressHandler">progress handler delegate</see> to use.</param>
        /// <param name="updateInterval">The minimum <see cref="TimeSpan"/> between progress updates.</param>
        /// <param name="sender">The source for this event.</param>
        /// <param name="name">The name to use with the event.</param>
        /// <param name="fixedTarget">A predetermined fixed target value to use with progress updates.
        /// If the value is negative the target is calculated by looking at the stream.</param>
        /// <remarks>This form is specialised for use within #Zip to support events during archive operations.</remarks>
        public static void Copy(Stream source, Stream destination,
            byte[] buffer, 
            ProgressHandler progressHandler, TimeSpan updateInterval, 
            object sender, string name, long fixedTarget)
        {
            if (source is null) {
                throw new ArgumentNullException(nameof(source));
            }

            if (destination is null) {
                throw new ArgumentNullException(nameof(destination));
            }

            if (buffer is null) {
                throw new ArgumentNullException(nameof(buffer));
            }

            // Ensure a reasonable size of buffer is used without being prohibitive.
            if (buffer.Length < 128) {
                throw new ArgumentException("Buffer is too small", nameof(buffer));
            }

            if (progressHandler is null) {
                throw new ArgumentNullException(nameof(progressHandler));
            }

            bool copying = true;

            DateTime marker = DateTime.Now;
            long processed = 0;
            long target = 0;

            if (fixedTarget >= 0) {
                target = fixedTarget;
            }
            else if (source.CanSeek) {
                target = source.Length - source.Position;
            }

            // Always fire 0% progress..
            ProgressEventArgs args = new ProgressEventArgs(name, processed, target);
            progressHandler(sender, args);

            bool progressFired = true;

            while (copying) {
                int bytesRead = source.Read(buffer, 0, buffer.Length);
                if (bytesRead > 0) {
                    processed += bytesRead;
                    progressFired = false;
                    destination.Write(buffer, 0, bytesRead);
                }
                else {
                    destination.Flush();
                    copying = false;
                }

                if (DateTime.Now - marker > updateInterval) {
                    progressFired = true;
                    marker = DateTime.Now;
                    args = new ProgressEventArgs(name, processed, target);
                    progressHandler(sender, args);

                    copying = args.ContinueRunning;
                }
            }

            if (!progressFired) {
                args = new ProgressEventArgs(name, processed, target);
                progressHandler(sender, args);
            }
        }

        /// <summary>
        /// Initialise an instance of <see cref="StreamUtils"></see>
        /// </summary>
        private StreamUtils()
        {
            // Do nothing.
        }
    }
}
